October 4th 1957 Sputnik just launched. Some physicists at John Hopkins at cafeteria were chatting. A couple of them asked if anyone had thought of listening to sputnik. They asked around and found a guy who was an expert on microwaves and had the facilities to do so. After a couple of hours of tinkering, they managed to pick it up. People came into the office to hear. They decided to record it. They started writing down the time stamps for the bleeps. They noticed frequency variations and thought they might be able to determine its speed using the doppler effect. They talked to colleagues thought if they looked at the slope of the doppler effects they could determine how far it is from their antennae. After getting permission to use the vax, after a couple of weeks they had mapped the whole trajectory having only listened to bleeps.
Couple of weeks later, their boss calls them into the office. You determined the satellite's unknown location from a known location on the ground. He asked if they could do the opposite. They thought, and number crunched and worked out it was easier. He wanted it for tracking nuclear subs to be able to torpedo Moscow! They thought about throwing up some satellites to track them. This was the birth of GPS.
12 minutes onwards in the video.
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